Experiments: The Origins
by TheSuperBuffMarsAngelMortal
Summary: PREQUEL TO EXPERIMENTS TMI SMUT! JACE/ISABELLE! What happens when an emotional Isabelle makes a deal with Jace that could change her outlook on life forever!
1. Chapter 1

**Experiments: The Origins**

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**Hi! I know you guys have been dying for this! Im so sorry its taken this long! If you're new to this series than it should be fine if you read this one first before reading Experiments. **

**It's SMUT LADIES AND GENTLEMEN! SMUT EVERYWHERE! **

**It's A prequel to Experiments ( s/9702989/1/Experiments ) is Isabelle and Jace Based and will be a lot slower than Experiments, more comedy and fun in this one and i PROMISE YOU THERE WILL BE NO ROMANTIC FEELINGS WHAT'S SO EVER BETWEEN ISABELLE AND JACE! The only love they have for each other is sibling love (now that i say that aloud its kind of twisted :l) ANYWAY! I hope you like it! ENJOY! AND REMEMBER I LOVE HEARING FEEDBACK FROM YOU GUYS! SO JSUT CLICK THAT LITTLE BUTTON! TYPE A FEW WORDS AND CLICK ANOTHER BUTTON AND THEN - DONE! YOU'VE REVIEWED! **

**HOPE YOU LIKE IT AS MUCH AS YOU LIKED Experiments! ENJOY!**

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**Chapter 1**

"You're a jerk! It's over!" Isabelle screamed into the phone before hanging up and throwing it on her bed as screaming in frustration.

"Whoa, what happened?"

She spun around on her heel to see her older 'adopted' brother, Jace, standing in her doorway, arms folded as he leaned against the frame, trying to hold back his smirk.

"Stupid Jackson, that's what!"

"Jackson? As in the Jackson that werewolf that asked you out at Taki's?"

"Yep! We've gone out a few times and he started… pressuring me." She practically whispered the last bit.

Jace was now standing dominantly, "He what?! Do you want me to get Alec, we'll go and teach him a lesson-"

"Jace! No! It just… it sucks that's all." She sighed as she plopped down on the bed, tucking her feet under her as she grabbed a pillow and held it close to her chest.

"What does?"

"I mean, I'm sure I'd be fine with doing that sort of thing with him but it's the fact of I've never done that and he has and what if I'm not good at it… you know?"

Jace was quiet for a moment, his expression unreadable before his lips quirked into a wicked smirk. He stepped into the room, closing the door behind him before drawing a locking and silence rune on the door before turning back to her.

"Jace, what are you-"

"I've got an idea."

"What is it?"

"Well, now, I was thinking I could help you out with your little problem."

"What?!"

"Oh come on Iz-"

"No way, you're like my brother!"

"How about, outside these four walls I'm you're brother but inside these four walls I'm-" He quickly pulled her up from the bed and clashed their lips together for a moment of passion before Izzy pulled back.

"I'm not going to have sex with you!"

"Not sex, and there'd be no feelings involved, it would be purely platonic… _experimenting_."

"_Experimenting_?"

"Yeah, we could use it as a learning experience, figuring out what feels good and what feels bad. Experimenting." He finalised with a small nod. "So are you in?"

Isabelle paused for a second and looked at the boy in front of her, he was not that much older than her but he was definitely well built, most Shadowhunters are, but she couldn't deny the certain _appeal_ Jace's body had on her. "Ok… when do we start?" She asked.

Jace answered her question by pulling her close once more and clashing their lips together, Isabelle slightly gasping, "Now?!"

"Now." He answered with a smirk.

"W-What do I do?" She asked.

Jace stepped back for a moment before slowly walking around her like a predator toying with his prey. "We'll start today, but it'll be a quick satisfaction, your benefit."

"Wha-"

"Tomorrow we'll go shopping."

"Why?"

"Well, no offense but your wardrobe consists of jumpers, baggy shirts, basic shorts and sweat pants, aside from your shadowhunter gear, and you should probably learn how to wear and walk in heels-"

"Why?"

"Sex appeal."

"Well you're wardrobe could do with some work as well! I mean if you want 'sex appeal' you could loose the sweat pants and baggy jumpers."

Jace shrugged, "I know, it's a mutual learning experience. You tell me what girls like; I'll tell you what boys like. Deal?"

"Deal. What do you want me to-"

"Lets work with kissing because from what I just experienced wasn't the greatest."

"HEY!"

"Honesty! Now… come here." He said with a smirk as he stepped forward, slightly gripping her waist. "How's this?"

"It's… good." She replied before slipping her arms up around his neck, "H-How's this?"

"Good." He said before leaning closer and pressing his lips against hers. They soon picked up a rhythm and Jace's hands were under her shirt, pressing against her back as Isabelle's hands went into his hair. Jace all of a sudden shoved his tongue in her mouth causing Isabelle to immediately pull away, "To much! To quick! Tongue! To much tongue!"

Jace nodded in response before kissing her once again, their rhythm was back and it was better… GREAT by Isabelle's standards. A small moan was released into the room as Jace's hands slid up under her shirt and gently started to tease her breasts.

Isabelle broke from the kiss as she rested her forehead in the nook of his neck her voice breathy, her skin burning from the simplest touch, "M-Maybe w-we should… um… m-maybe we sh-should s-stop, f-for tod-day."

Jace's breath was raged as his forehead leaned the top of her head, his hands shakily slipping out of her shirt, "Maybe we should." There was a beat of silence before Jace stepped away from her. "Ok… tomorrow, at three we go shopping, I'll meet you out front around two thirty." With that he spun around and bolted back to his room, leaving a very breathless Lightwood standing mindlessly in her room. Jace practically jogged into the shower, turning on the hot water as his hand slipped down and grasped himself. In a shout of ecstasy his heat went down and all he could think was '_This is going to be fun!'_

**_DID YOU LIKE IT? PLEASE REVIEW AND FAVOURITE AND FOLLOW!_**


	2. Chapter 2

**sorry it's a bit late guys, i hope to get these updates being a bit more frequent. But here it is! Hope you like it!**

**ENJOY!**

**Chapter 2 – Sexual Frustration Much?**

"Move it Iz!" Jace said as he banged on her bathroom door.

"I'm coming!"

Jace let out an irritated sigh as he leaned against the wall, "If you don't come out anytime soon, I'm coming in to get you!"

Just then the door swung open, "I'm out! Happy! Geeze! First you and Alec put me through one of the most intense training sessions and then you rush my shower so we can go shopping! I don't even understand why we're doing this anyway."

"Because the only time I've seen you look good is when you're in your fighting gear, the rest of the time you're in this." He says gesturing to her clothes, "Sweat pants and baggy shirts, you're hair not even properly done, just pulled back into a messy bun –"

"Hey! Have you looked at yourself in the mirror? Because you're not the greatest looking either!"

"I know, that's why we're going shopping for the both of us. Ok, are you ready or what?"

"Fine, let's hurry up get this over with then!"

**_6 hours later_**

Isabelle and Jace made their way to their separate rooms as they each carried at least 15 different shopping bags. Both annoyed and frustrated of each other after their exhausting day of shopping – which consisted of shouting, yelling, a few tears at one point and Isabelle giving Jace a good clock in the jaw when he commented on her face and how she'd look better with make-up.

With a slam of her door Isabelle let out a frustrating scream as she threw the bags on the floor before running back out and down to the training room. After many punches and kicks of the punching bag the door swung open.

"What are you doing in here?!" Jace practically shouted at her as he slammed the door closed behind him.

"It's a free country!" She spat back as she kicked the punching bag so hard it flew off the hook and collided into the wall.

Jace just groaned as he plucked a few throwing knives from the wall before he started randomly throwing them at different targets around the room. As Isabelle walked over to the ladder that leads up to the balancing beams a knife struck the wall, right next to her head. She quickly spun around and glared at him. "Childish!"

"Says the girl who started crying in lingerie store!"

"You made me cry!"

"You're a shadowhunter!"

Now she was fuming, she stormed over to him and as she shoved him she screamed, "I'M ALSO A GIRL!" Another shove, "YOU CANT EXPECT TO SPEND THE A WHOLE DAY INSULTING A GIRL!" She now had him pinned against the wall, "AND NOT EXPECT HER TO BREAK AT SOME POINT!" At this point she pulled him forward slightly before shoving him back against the wall, "YOU CALLED ME UGLY!" She gave him a strong hit to the jaw, "YOU CALLED MY FASHION SENSE DISGUSTING!" Another strong clock to the jaw, "AND YOU CALLED ME PATHETIC!" She slammed him against the wall again, "AND THAT'S JUST THE CLIFFNOTES!" Her eyes burned with hate as she held him there but she soon found herself stumbling back as Jace pushed her back off him, "FUCK YOU IZ! I WAS TRYING TO HELP! NOT LIKE YOU WERE ANY HELPFUL TO ME! YOU KEPT SAYING 'not tight enough! Not tight enough! Blue doesn't suit you! Blah blah blah!' I'M SO SICK OF YOUR VOICE!"

"PISS OFF!"

"SHUT UP!"

"MAKE ME!"

And he did.

He gripped the back of her neck and smashed their lips together. Both fighting for dominance as they put all their anger and frustration into the one kiss until they had to pull back to breath.

Jace's eyes were now glazed over with lust as he grabbed her hand and dragged her out of the training room.

"W-Where are we – are we going?" Isabelle said breathlessly as she stumbled behind him.

"Your room, remember? I'm your brother outside those four walls so-" He now pushed her into her room, kicking the door behind him before capturing her lips as his once again before pulling back with a proud smirk, "I couldn't do that."

Isabelle was too dazed to care as he lead her over to the bed and sat her down, giving her a quick kiss before pulling her jumper over her head and tossing it to the side. Jace quickly removed his own top as he crawled on top of her, gently pushing her to lay back against the bed, the whole time their lips locked. Isabelle's hands instinctively wrapped around him, running up his back before gripping his shoulders and pulling him closer. Jace's lips were now trailing down her neck and chest, he placed butterfly kisses along the mounds of her breasts as he slipped a hand behind her and tried to unhook her bra. "Crap." Jace hissed out as his hands fumbled with the clasp. Isabelle quickly unclipped it for him but let him take it off. Jace slowly slipped the straps down her arms before slowly taking it off her; a low growl escaped his throat as he saw her perfect, perky breasts. He couldn't pull his eyes away from her as his hands slowly ran up her sides, starting from her thighs, up her hips and waist until he slowly took both perky breasts in his hands. His thumbs circling her aroused nipples, which caused a pleasurable shudder to escape the brunet. Isabelle's back arched, instinctively wanting more. Jace hesitated for a moment before capturing one of her breasts in his mouth and teased it the best he could. A loud, long moan was released into the room as his tongue flicked over her hard nipple – he took this as encouragement and repeated this action several times. Isabelle's nails dug into the sheets as he moved his afflictions to her other breast. Isabelle couldn't think straight, she's never experienced anything like this, sure, she's heard about it and thought about it but she never knew it could be this good.

Through all her moaning she was able to stutter out "M-More!"

Jace was confused for a second but got the gist of it. He slowly kissed his way down her stomach and soon he reached the edge of her white cotton underwear. His fingers shook as he slipped them off and down her legs and tossed them to the side. He was scared and worried he'd stuff up but he persevered. His hands ran back up her legs and they instinctively separated. Izzy unknowingly raised her hips, silently begging for more. Jace ran his tongue across her slit and slightly moaned at the taste, it was intoxicating and addictive. His tongue separated the lips as he dove in and experimented. First he just ran it up and down, a few moans escaping the brunette but he stopped over a certain bud of nerves as she screamed his name. He decided he'd put his focus on that small bud, his tongue swirling and flicking the bud. She was soaking now; it was starting to leak down her thighs. Isabelle back was permanently arched, one hand locked onto the head board the other locked in Jace's blond locks, pushing him to deepen the pleasure. Jace went on an instinct and lightly nipped the bud with his teeth. Isabelle screamed and slightly shook as her orgasm ran over her like a river. Jace held her legs apart, his lips attached to her bud as she rode out the immense pleasure. Isabelle collapsed against the bed, her entire body falling limp with exhaustion, her chest rising and falling as she tried to regain her breathing. Jace licked all her explosive juices, moaning at the addictive taste. His hands slowly ran up her thighs and hips as he slid up her, placing soft kisses up her body before he reached her panting lips. Her body was covered with a small layer of sweat and Jace couldn't help but grin at the thought that he'd made her like this. He slowly stood up from the bed and pulled on his shirt.

"But…" Iz panted out, "Don't. You. Want. Me. Too… you know. On you?"

Jace grinned down at her, "Oh trust me, you will but you look exhausted, get some rest. But I will be back." With that Jace left, leaving Isabelle in a pleasurable numbness.

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